Fuel oil



thousand barrels of base fuel. .may contain other additives such an anti-oxidants, pour depressons, rust inhibitors, etc.

* atent 3,88,815 Patented May 7, 1963 fire 3,038,315 FUEL OIL Stanley C. Haney, Homewood, and .loseph A. Verdol,

Dalton, Ill., assignors, by mesne assignments, to Sinclan- Research Inc, New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 27, 1953, Ser. No. 724,254

, 5 Claims. (Cl. 4471) Thefpresent invention relates to fuel oil compositions of improved thermal stability. More particularly, the invention is concerned with fuel oil compositions containing certain high temperature stability additives which compositions are capable of preventing. or inhibiting the formation of fuel degradation'particles'when utilized under high temperature conditions.

Hydrocarbon fuels, for example, those distilling in the range from about 150 to 700 F., generally contain impurities such as moisture, dispersed water, organic and/ or inorganic matter which at high temperatures tend to form insoluble products. These insoluble products settle out and adhere to surfaces with which they come in contact and invariably cause the clogging or plugging of the small and narrow areas of the equipment in which they are used. This necessitates frequent cleaning and even replacement of parts thereby markedly decreasing the performance efficiency of various equipment.

The formation of fuel degradation particles and the problems created thereby are particularly common in jet and gas turbine engines which contain hot fuel line sections capable of inducing fuel degradation and small passages such as fuel metering equipment, filters, nozzles and the like in which the particles may lodge to cause plugging or clogging.

In the present invention, we have found that the addition of relatively small amounts of the liquid product obtained by reacting approximately equal molar portions of a dibasic acid or an anhydride or ester thereof with an alkyl substituted dialkanolamine to a non-viscous liquid hydrocarbon fuel provides compositions of high temperature stability and therefore of reduced plugging tendencies. The nitrogen-containing ester thus formed can be added to the hydrocarbon base fuel inamounts of about one pound to about 100 pounds per thousand barrels. There appears to be no need to add more than 100 pounds per thousand barrels of base fuel. Preferably, the ester should be added in an amount of about 5 'to 50 pounds per Our novel composition The non-viscous liquid hydrocarbon base fuel of our invention include, for example, kerosenes, diesel fuels, domestic fuel oils, jet engine fuels such as LIP-3, ]P-4 and JP-S specification fuels, and other broad or narrow petroleum-derived distillate fractions of similar boiling range. In general these base fuels have essentially an ASTM distillation range above about 150 F., for instance, in the range of about 190 to 700 F. with the 90 percent .point being at least about 450 F. Certain of these fuel distill in the range of about 400 to 650 F., and the more desirable of the fuels have API .gravities of about 35 to 50. These fuels may contain cracked as well as straight run components and the cracked materials will frequently be about 15 to 70 volume percent of the fuel.

The dibasic acids which can be utilized in forming the esters of the present invention conform to the following general structural formula:

ester and the dial kanolamine.

.8 to 38 carbon atoms, preferably 8 to 24 carbon atoms.

By the term non-aromatic in nature, we mean to include not only aliphatic hydrocarbon acids but also those acids which are normally unsaturated and monobasic in nature but have been converted to dibasic acids by dimerization, as well as cyclic naphthene dibasic acids. Examples of suitable acids are dodecylsuccinic dodecenylsuccinic, octadecylsuccinic, octadecenylsuccinic, dimerized unsaturated fatty acids such as linoleic, ricinoleic etc. Not only are the dibasic acids useful but also their anhydrides and esters can be employed, but in any case the reaction product is that of the corresponding dibasic acid for instance, when an ester is employed, the esterifioation liberates the alcohol of the ester group.

The alkyl substituted dialkanolamines useful in preparing the esters of the present invention are those having the following general formula:

wherein alkyl substituent R contains about 4 to 20 carbon atoms and R" in each case above is a branched or straight chain alkyl group of 2 to 4 carbon atoms. Examples of useful alkyl substituted dialkanolamines can be enumerated as follows: butyldiethanolamine, octyldiethanola-mine, octadecyldiethanolamine, octadecyldiisopropanolamine, etc.

Preparation of the esters of this invention can be by either of two general methods, i.e. they can be prepared by direct esterification of the dibasic acid or anhydride with the dialkanolarnine or a dibasic acid ester can be prepared by any of the recognized procedures and the desired ester prepared by ester interchange between the acid The two methods above of preparing the ester compounds of the present invention are illustrated in the following Examples 1 and II which are not to be considered as limiting. In the examples, the reaction providing the high stability additive of this invention was continued until the acid number was close to zero, e.g. not more than about 2 to pH of 11, which is the preferred procedure.

EXAMPLE I Preparation of Ester by Direct Esterification A mixture of'17 8 grams of dodecenylsuccinic anhydride (0.665 'mole) and 245 grams of octadecyldiethanolramine (0.665 mole) was placed in a 300 ml. 4-necked flask equipped with a Claisen head, condenser, thermometer and gas inlet tube through which nitrogen was bubbled during the reaction period. Approximately 0.2 gram of zinc stearate was added-to the flask as a catalyst. The flask was heated under atmospheric pressure for about three hours at about 200-210 C. whereupon 4 mls. of water was collected. The reaction mixture was subsequently heated to 200 C. in vacuum under about 6-10 mm. of pressure for an additional 21 hours. The resultant product was a straw-colored, viscous polymer having the following properties:

Molecular weight 1 1,480

1 Freezing point method.

Table I below shows other esters and their physical properties which esters were prepared by direct esterification employing a procedure similar to Example I:

I All molecular weights were determined by the freezing point method.

EXAMPLE II Preparation of an Ester by Ester Interchange A mixture of 192.8 gms. (0.5 mole) of octadecyldiisopropanolamine and 115.1 gms. (0.5 mole) of dimethyl sebacate was placed in a 300 ml. 4-necked flask equipped as described in Example I. 1.5 grams of tetraisopropyltitanate (an ester interchange catalyst) was added to the flask. The mixture was heated under nitrogen at atmospheric pressure until methanol no longer distilled from the reaction mixture. The reaction mixture was then heated in vacuo at 200 C. until the total heating time was about 24 hours. At the end of the heating period, an oil-soluble, amber colored polymer was obtained. Analysis of the polymer showed the following:

Molecular weight 1 1,080

1 Freezing point method.

It is believed that the reaction of the dibasic acids or anhydrides or esters thereof and the alkyl dialkanolarnines of this invention, yield esters conforming to the following general formula:

wherein R and R and R" are as described above, and y is an integer of 1 up to the limit of compatibility of the ester with the base fuel, preferably, y should be about 1 to 10. Compatibility is used to mean soluble, miscible or otherwise dispersible in the base fuel without continued agitation and in the amounts required to impart increased thermal stability to the base fuel. Also, R and R advantageously have a total number (one R plus one R) of carbon atoms of about 20 to 44.

The following example will serve to illustrate the compositions of the present invention but is not to be considered limiting,

EXAMPLE III In accordance with the procedures outlined in Example I above, the following esters were prepared.

and dodecylsuccinic The following ester was prepared in accordance with the procedure outlined in Example II above.

Ester from:

E-octadecyldiisopropanol and dimethyl sebacate Each of the esters prepared was added to a hydrocarbon base fuel composed of 70 volume percent of kerosene and 30 volume percent of cracked naphtha in concentrations of 16.5 and 33 pounds of ester per thousand barrels of base fuel. The physical properties of the base fuel and its constituents are shown in Table II.

Table II Composition:

Vol. percent kero one Vol. percent cracked naphtha Laboratory tests:

Gravity, APT Flash F Pour, F

Freezing point, F. Smoke p0int Bromine numb Percent sulfu. Percent olefins.

Below Below -76 15 The fuel compositions thus prepared were tested in a Cooperative Fuels Research coker to determine the effect of the ester additive contained therein for improving high temperature stability. In this apparatus, the fuel compositions were pumped through a preheater tube which was heated to a temperature of 300 F. and then through a filter section heated to a temperature of 400 F. The base or neat feed was similarly treated for purposes of comparison.

The test fuel enters the inlet body of the preheater and passes between the inner and outer aluminum tubes, where it is heated to the 300 F. temperature by an electric heater inserted in the inner tubes. The preheater tube has a section 13 inches long over which the hot fuel flows and the deposit condition of the tube is rated in inches by the following code:

0-No visible deposits 1-Visible haze or dulling but no visible color 2B arely visible discoloration 3Light tan to peacock stain 4-Heavier than code 3 The preheater simulates, for example, jet fuel line sections of jet or gas turbine engines as typified by an engine fuel-oil cooler and/ or high temperature transfer lines. Leaving the preheater outlet body, the fuel enters the heated filter section. The heated filter represents the small passages on fuel metering equipment and nozzle .areas of the engine where fuel degradation particles may become lodged. A precisioned sintered steel filter in the heated filter section traps fuel degradation particles formed during the .test and the extent of the deposit buildup is measured as a pressure drop across the test filter. Pressure taps before and after the filter section are connected to a mercury manometer to indicate filter pressure drop.

Each test was run for 300 minutes or until the pressure drop across the filter reached 25 inches of mercury. The pressure drop at the end of the runs was recorded as well as the number of minutes required to reach pressure drops of 10 and 25 inches of mercury. The deposit condition of the preheater tube was also rated and recorded. The test results are shown in Table III.

Table [11 Test conditions:

Preheater temperature 300 F.

Filter temperatute 400 F.

Fuel flow rate 6 lbs/hour.

Fuel pressure 150 p.s.i.g.

Preheater deposits Conc., Time to Time to AP at 300 Additive lb./M reach AP reach AP min. or

bbls. of 10 in. of 25 in. end of run, Inches Inches Inches Inches Inches Hg, mm. Hg, min. in. Hg of of of of of code 4 code 3 code 2 code 1 code N at fu l- 105 21s 25 0 3 0 0 10 A 33 210 211 25 0 4 0 0 9 16. 300+ 300+ 0. 63 4 0 1 0 8 33 300+ 300+ 0. 70 0 4 0 0 9 16. 5 300+ 300+ 0. 02 0 0 3 0 33 300+ 300+ 0. 57 4 0 1 0 8 1o. 5 300+ 300+ 1.15 0 3 1 1 s 33 300+ 300+ 0.15 0 0 4 0 9 16. 5 300+ 300+ 0. 13 0 0 4 2 7 33 300+ 300+ 0. 37 3 2 0 0 8 16. 5 300+ 300+ 0. 85 4 0 l 0 8 EXAMPLE IV rels of fuel was used, the preheater dep osits were ad- Additive B, the ester from octadecyldiethanol-amine and dodecenylsuccinic anhydride of Example III was added to a straight run kerosene from Mid-Continent crude in concentrations of 5 and 10 pounds per thousand barrels of kerosene. The kerosene employed had an API gravity of 43.4 and a boiling point of 33-6 to 493 F. The fiuel composition thus prepared was tested as in Example III.

Similarly additive C (ester of octadecyldiethanolamine and octadecenylsuccinic anhydride) of Example III was added to the kerosene in a concentration of eight pounds of ester per thousand barrels of kerosene and the fuel composition tested as in Example III.

The test results are shown in Table IV.

Test conditions Preheater temperature, F 400 Filter temperature, F 500 Fuel flow rate, lbs/hr 6 Fuel pressure, p si c 150 Examination of Tables III and IV shows that all of the additives reduced filter plugging considerably. For example, comparing in Table III the tests on the tfiuel compositions with the test on the neat fuel, it is seen that the delta pressure at the end of the run on the neat fuel was whereas the delta pressure at the end of the runs of the novel fuel compositions was with one exception at the highest 1.115, and in most cases well below 1.0. As indicated by the data, the only exception was when additive A was employed in concentrations of 33 pounds per thousand barrels of tuel. To be most effective additive A should be employed in concentrations of about 10 to 215 pounds per thousand barrels of fuel.

Whereas all of the additives of the present invention reduced filter plugging considerably certain of them when added in particular concentrations showed advantages over the others with respect .to preheater deposits. For example, when additives A, C, or E in concentrations of 16.5 and 33 pounds/100 barrels of fuel or additives -B or D in concentrations of 110 pounds or less/1000 barrels of fuel were employed, no enhancement of the neat [fuel with respect to reduced preheater deposits is round. However, when additive B in concentrations of about 16.5 pounds/ 1000 barrels of tuel or additive D in concentrations of about 16. 5 pounds and about 33 pounds/1000 barvantageously reduced. Thus we prefer to employ additive D in concentrations of at least about 115 pounds/1000 barrels of tfuel or additive B at about 15 to 25 pounds/ 1000 barrels of feed.

We claim:

1. A fuel composition consisting essentially of a hydrocarbon fuel base distilling in the range of about 150 to 700 F. having a 90 percent distillation point of at least about 450 F. and about 1 to 100 pounds per 1000 barrels of said hydrocarbon fuel of an ester characterized by the formula:

wherein R is a non-aromatic divalent hydrocarbon radical containing 8 to 38 carbon atoms, R is an alkyl radical containing 4 to 20 carbon atoms, R" is an alkyl group of 2 to 4 carbon atoms, R and R contain a total of 20 to 44 carbon atoms and y is from 1 to an integer providing a 'fuel compatible ester, said amount of ester being sufficient to provide a composition of high temperature stability.

2. The fuel composition of claim 1 in which the base fuel contains cracked components.

3. The fuel composition of claim 1 whereby R is the divalent hydrocarbon radical of dodecenyl succinic acid, R is an octadecyl radical and R" is an ethylene radical, and the additive is present in the amount of about 15 to 25 pounds per 1000 barrels of hydrocarbon fuel.

4. The fuel composition of claim 1 wherein the amount of ester is about 5 to 50 pounds per 1000 barrels of hydrocarbon fuel.

5. The fuel composition of claim l wherein R is the divalent hydrocarbon radical of dodecenyl succinic acid, R is a butyl radical and R is an ethylene radical and the additive is present in the amount of about 15 to 50 pounds per 1000 barrels of hydrocarbon fuel.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A FUEL COMPOSITION CONSISTING ESSENTIALLY OF A HYDROCARBON FUEL BASE DISTILLING IN THE RANGE OF ABOUT 150 TO 700*F. HAVING A 90 PERCENT DISTILLATION POINT OF AT LEAST ABOUT 450*F. AND ABOUT 1 TO 100 POUNDS PER 1000 BARRELS OF SAID HYDROCARBON FUEL OF AN ESTER CHARACTERIZED BY THE FORMULA: 